Use of biodegradable polymers in preventing scale build-up

ABSTRACT

A biodegradable scale inhibitor and dispersant is provided. The scale inhibitor includes a copolymer comprising at least one of N-oxygenatedhydrocarbonamide monomers and at least one of amino acid monomers. A method of reducing scale build-up on heating exchanger surfaces that come in contact with an industrial water is provided by adding a copolymer comprising at least one of N-oxygenatedhydrocarbonamide monomers and at least one of amino acid monomers to the water system such as cooling towers.

BACKGROUND OF THE INVENTION

The present invention relates generally to the protection of metallicsurfaces from scaling and the accumulation of other deposits. Morespecifically, the present invention relates to scale inhibitingcompositions, dispersants and methods of using the same.

To efficiently transfer heat from a metal surface, such as the insidesurface of a boiler or heat exchanger tube, to any liquid medium such aswater, or vice versa, the surface of the metal should be as clean and asfree of scales and deposits as possible. Simply put, scaling and otherdeposits on the metal surface will reduce the rate of heat transferbetween the metal surface and the water or other fluid medium andtherefore scaling and deposits will reduce the efficiency of the system.Further, scaling and deposits can lead to premature corrosion ofmetallic surfaces.

The most common way to combat scaling and deposit accumulation inaqueous systems is to add scale-inhibiting additives and dispersants tothe feedwater or solution. However, currently available scale-inhibitingadditives and dispersants are nonbiodegradable, which limits theapplicability of such additives.

Scaling and deposits in industrial heat exchange systems may come in avariety of forms and originate from a variety of sources. Typically,scales and deposits are caused by calcium ions, magnesium ions, ironions, zinc ions and clay particulates.

More specifically, said scales and deposits include but are not limitedto alkaline earth metal phosphates, alkaline earth metal carbonates,alkaline earth metal sulfates, iron (hydro)oxides, zinc hydroxides,manganese oxides, aluminum (hydro)oxides, clays and silicates.

For example, industrial water, such as the water used in cooling towers,heat exchangers and boilers, is often treated with a variety ofinorganic and organic phosphorus-containing compounds. These compoundstend to produce calcium phosphate and magnesium phosphate scales whichadhere to cooling tower surfaces, heat exchanger tubes, and boilersurfaces.

Further, soluble iron may be introduced into an aqueous system by itspresence in the feedwater or in other ways. Soluble iron is generallybelieved to be iron in the form of Fe⁺⁺. Soluble iron, as this term isused herein, does not exclude, however, other forms of iron that aresoluble in a given water system. In aqueous systems, and particularlyindustrial aqueous water systems, the presence of soluble iron in thefeedwater, or the introduction of a soluble iron species into the systemby other means such as corrosion, can lead to the undesirableprecipitation of iron oxides and iron hydroxides which may settle andaccumulate as deposits on surfaces that come in contact with the water.Such precipitates commonly occur where water containing soluble ironions is changed to a more oxidation-prone environment. Also,precipitation will occur where an oxidizing agent such as oxygen,chlorine and the like is introduced or increased.

Further, many industrial water systems such as those used in theoperation of cooling towers are treated with soluble zinc salts. Suchsoluble zinc salts tend to form undesired scales in alkaline solutionsor in the presence of other precipitating anions such as phosphate.

Finally, clay particulates may be introduced into an aqueous system bythe presence of clay in the feedwater. Accumulation of clay particulatestends to form deposits on metallic heat exchangers or metal surfaces ofboilers.

The aforementioned scales and deposits reduce heat transfer, acceleratecorrosion or cause other problems resulting in reduced systemefficiencies.

Currently, certain polyacrylates and polyacrylamides are used to inhibitthe build-up of scales in aqueous systems. However, polyacrylates andpolyacrylamides are not biodegradable and thus accumulate in theenvironment upon release from the water treatment systems. Thus, thereis need for biodegradable compositions that are capable of inhibitingthe build-up of scales and deposits on metallic surfaces. Althoughpolyaspartic acid is biodegradable, it does not effectively inhibit thebuild-up or scales and deposits on metallic surfaces.

SUMMARY OF THE INVENTION

The present invention provides a family of compositions that reduce orinhibit development and build-up of scales and deposits on metallicsurfaces and a method of reducing development and build-up of scales anddeposits on metallic surfaces. The family of compositions provided bythe present invention includes copolymers comprising at least one ofN-oxygenatedhydrocarbonamides and at least one of amino acids.

The scale inhibiting compositions of the present invention comprisecopolymers comprising at least one N-oxygenatedhydrocarbonamide or itssalt of the general formulas I-α and I-β as shown below with at leastone amino acid compound having the general formula (II) as shown below.

The N-oxygenatedhydrocarbonamide or salt thereof of the general formulasI-α and I-β are as follows: ##STR1## or a mixture of forms I-α and I-βin ratios ranging from 1:99 to 99:1 and wherein M may be hydrogen, ametal, an alkali metal ion, an alkaline earth metal ion or NH₄ ⁺, Al⁺³,Fe⁺³, Fe⁺², Zn⁺¹ or mixtures thereof; m ranges from 1 to 10; n may be 1or 2; R¹ may be hydrogen, a C₁ to C₃₀ alkyl group or an aryl group or analkyl or aryl group that is substituted with one or more of OH, SO₃ M(wherein M is H or a metal), PO₃ M₂ (wherein M is H or a metal), COM(wherein M is OH, OR, or NR₂ wherein R is an alkyl of 3 to 4 carbonatoms); X may be a C₁ to C₃₀ alkylene or arylene; Y may be H, a C₁ to C₄alkyl, SO₃ M' or a mixture thereof wherein M is a H or a metal ion.

Further, X may be a straight or branched-chain alkylene group having oneto thirty carbon atoms or a straight or branched-chain alkylene orarylene group substituted with one or more of the following: OH, SO₃ M'(wherein M' is H or metal), PO₃ M₂ (wherein M is H or metal), COM(wherein M is OH, OR, or NR₂ wherein R is an alkyl of 3 to 4 carbonatoms).

Still further, X(OY)_(m) may be --CHR³ CH₂ (OCHR³ CH₂)_(p) (OCH₂CH₂)_(o) OR⁴ or --CH₂ CH₂ (NR⁵ CH₂ CHR⁶)_(r) OR⁴ where R³ is H or CH₃ ormixtures thereof; o ranges from zero to 50; p ranges from zero to 50;o+p ranges from 1 to 50; r ranges from zero to 50; R⁴ is a C₁ to C₄alkyl group; R⁵ is a C₁ to C₄ alkyl group; R⁶ may be H, CH₃ or SO₃ Mwhere M may be H, alkaline metal ions or N(R⁷)₄ where R⁷ is H, a benzylgroup or a C₁ to C₄ alkyl group.

The amino acid compound having the general formula (II) is as follows:##STR2## wherein R₃ is a radical defined by the list of amino acids andamino acid derivatives appearing below. If formula (II) is asparticacid, the aspartic acid unit in the copolymer is in its αform or βformor a mixture form of α:β ranging from 99:1 to 1:99.

The amino acids of the general formula (II) (wherein M is H, a metal,alkaline metal ions, earth alkaline metal ions, NH₄ ⁺, Al⁺³, Fe⁺², Fe⁺³or mixtures thereof) include alanine, arginine, aspartic acid,asparagine, cysteine, glutamine, glutamic acid, glycine, histidine,isoleucine, leucine, lysine, methionine, serine, threonine, tryptophan,tyrosine, valine, proline and phenylalanine. The following amino acidderivatives can be utilized as well; hydroxyproline, γ-carboxyglutamicacids or salts thereof, o-phosphoserine, o-phosphotyrosine,o-sulfoserine, o-sulfotyrosine, o-phophothreonine, o-sulfothreonine,s-sulfocysteine, s-phosphocysteine, side chain N-substituted asparaginewith C₁ to C₃₀ alkyl, aryl, alkyl or sulfoalkyl, o-sulfoaryl,o-sulfoalkyl, o-phosphoalkyl, o-phosphoaryl, o-phosphoalkyl,c-sulfonoaryl, c-sulfono alkyl, c-sulfonoalkyl, --(--CH₂ CH₂ O--)_(s)--R² and --(--CH₂ CH₂ NR² --)_(t) --R³, where R¹ and R² are H or a C₁ toC₄ alkyl group and R³ is a C₁ to C₄ alkyl group, both s and t range from1 to 50.

The repeating molar units of formulas I-α and I-β linked in thecopolymer backbone are described as the following: ##STR3##

The repeating molar units of formula II linked in the copolymer backboneare described as the following: ##STR4##

If the amino acid of formula II is aspartic acid or its salts, theaspartic acid repeating molar units linked in the copolymer backbone aredescribed as shown below: ##STR5##

All D, L and DL-optical sources of formula I and II monomers can beutilized.

The molecular weight of the polymers of the present invention can varyfrom about 500 to about 200,000. A preferred molecular weight range isfrom 500 to 80,000; a more preferred molecular weight range is from 500to 40,000.

The copolymers of the present invention are biodegradable and extremelyeffective scale inhibitors of alkaline earth metal phosphates such ascalcium phosphate and magnesium phosphate. The above copolymers are alsoeffective in inhibiting scales and deposits of alkaline earth metalsulfates, iron (hydr)oxide, zinc hydroxide, aluminum (hydr)oxide, clays,calcium carbonate, silicates and other scales. These biodegradablecopolymers are highly calcium tolerant. The polymers of the presentinvention are more effective and efficient as dispersants and scaleinhibitors than unmodified polyamino acids such as unmodifiedpolyaspartic acids.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-2-hydroxyethylaspartamide or N-2-hydroxyethylglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) N-3-hydroxypropylaspartamide or N-3-hydroxypropyglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-2-hydroxypropylaspartamide orN-2-hydroxypropyglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-1-methyl-2,3-dihydroxypropylaspartamide orN-1-methyl-2,3-dihydroxypropyglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-1-ethyl-2,3-dihydroxypropylaspartamide orN-1-ethyl-2,3-dihydroxypropyglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-2,3-dihydroxypropylaspartamide orN-2,3-dihydroxypropyglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-1-hydroxymethyl-2,3-dihydroxypropylaspartamide orN-1-hydroxymethyl-2,3-dihydroxypropyglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-bis(2-hydroxyethyl)aspartamide orN-bis(2-hydroxyethyl)glutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-(3-bis(N-hydroxyethyl)amino)propyl-1-amidoaspartamideor N-(3-bis(N-hydroxyethyl)amino)propyl-1-amidoglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-p or O- or m-phenolaspartamide or N-p or O- orm-phenolaspartamideglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-2(2-hydroxyethoxy)ethylaspartamide orN-2-(2-hydroxyethoxy)ethylglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-dihydroxyphenylaspartamide orN-dihydroxyphenylglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of a general formula(I) is N-2-(2-hydroxyethoxy)ethylaspartamide orN-2-(2-hydroxyethoxy)ethylglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-2-(2-hydroxyethylamino)ethylaspartamide orN-2(2-hydroxyethylamino)ethylglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-2-methoxyethylaspartamide or N-2-methoxyethylglutamide.

In an embodiment, the N-oxygenatedhydrocarbonamide of the generalformula (I) is N-(2-o-sulfatoethyl)aspartamide orN-(2-o-sulfathoethyl)glutamide.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is aspartic acid.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is glutamic acid.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is asparagine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is glutamine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is histidine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is arginine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is lysine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is alanine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is cysteine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is glycine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is isoleucine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is leucine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is methionine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is proline.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is serine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is threonine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is tryptophan.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is tyrosine.

In an embodiment, the amino acid compound of the general formula (II)(wherein M is H or metal) is valine.

An advantage of the present invention is to provide a new family ofwater soluble polymers which are biodegradable and which are effectivescale inhibitors and dispersants.

Another advantage of the present invention is to achievehigh-performance scale inhibition using alkanolamine modified polyaminoacids.

Still another advantage of the invention is to provide a family ofbiodegradable polymers which simultaneously disperse particulate matterand inhibit many types of scales in aqueous systems, especially inindustrial aqueous systems.

Another advantage of the present invention is to provide a method ofachieving high-performance scale inhibition using alkanolamine modifiedpolyamino acids.

Another advantage of the present invention is to provide a method ofreducing scale and deposit build-up by utilizing a new family of watersoluble polymers which are biodegradable and are effective scaleinhibitors and dispersants.

Another advantage of the present invention is to provide an improvedscale and deposit inhibiting composition for use in connection withmetallic surfaces.

Still another advantage of the present invention is to provide animproved scale and deposit inhibiting composition that is biodegradable.

A further advantage of the present invention is to provide an improvedscale and deposit inhibiting composition which also reduces corrosion.

Yet another advantage of the present invention is to provide a new usefor N-oxygenatedhydrocarbonamide and salts thereof.

Another advantage of the present invention is to provide a new use foramino acids and salts thereof.

A further advantage of the present invention is to provide improvedscale-inhibiting compositions which have aqueous and non-aqueousapplications.

Additional features and advantages are described in, and will beapparent from, the detailed description of the presently preferredembodiments.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The present invention provides an improved scale and deposit inhibitingcomposition that is environmentally acceptable. In a preferredembodiment, the scale inhibiting composition is a copolymer comprisingat least one of N-oxygenatedhydrocarbonamide monomers and at least oneof an amino acid monomers. The N-oxygenatedhydrocarbonamides or saltthereof of the general formulas I-α and I-β as shown below: ##STR6## ora mixture of forms I-α and I-β in ratios ranging from 1:99 to 99:1 andwherein M may be hydrogen, a metal, an alkali metal ion, an earthalkaline metal ion or NH₄ ⁺, Al⁺³, Fe⁺³, Fe⁺², Zn⁺¹, or mixturesthereof; m ranges from 1 to 10; n may be 1 or 2; R¹ may be hydrogen, aC₁ to C₃₀ alkyl group or an aryl group or alkyl or aryl group havingfrom one to thirty carbon atoms, or an alkyl or aryl group that issubstituted with one or more of OH, SO₃ M (wherein M is H or a metal),PO₃ M₂ (wherein M is H or a metal), COM (wherein M is OH, OR, or NR₂wherein R is an alkyl of 3 to 4 carbons); X may be a C₁ to C₃₀ alkyleneor arylene (straight or branched) or a straight or branched-chainalkylene group having one to thirty carbon atoms or a straight orbranched-chain alkylene or arylene group substituted with one or more ofOH, SO₃ M (wherein M is H or a metal), PO₃ M₂ (wherein M is H or ametal), COM (wherein M is OH, OR, or NR₂ wherein R is an alkyl of 3 to 4carbons); Y may be H, C₁ to C₄ alkyl, SO₃ M or mixture thereof wherein Mmay be hydrogen or a metal ion.

Further, X (OY)_(m) may be --CHR³ CH₂ (OCHR³ CH₂)_(p) (OCH₂ CH₂)_(o) OR⁴or --CH₂ CH₂ (NR⁵ CH₂ CHR⁶)_(r) OR⁴ where R³ is H or CH₃ or mixturesthereof; o ranges from zero to 50; p ranges from zero to 50; o+p rangesfrom 1 to 50; r ranges from zero to 50; R⁴ is a C₁ to C₄ alkyl group; R⁵is a C₁ to C₄ alkyl group; R⁶ may be H, CH₃ or SO₃ M where M may be H,earth metal ions, alkai metal ions or N(R⁷)₄ where R⁷ is H, a benzylgroup or a C₁ to C₄ alkyl group.

Acceptable examples of the N-oxygenatedhydrocarbonamide compounds of thegeneral formula (I) include N-2-hydroxyethylaspartamide orN-2-hydroxyethylglutamide, N-3-hydroxypropylaspartamide orN-3-hydroxypropylglutamide, N-2-hydroxypropylaspartamide orN-2-hydroxypropylglutamide, N-1-methyl-2,3-dihydroxypropylaspartamide orN-1-methyl-2,3-dihydroxypropylglutamide, N-1-ethyl-2,3-dihydroxypropylaspartamide or N-1-ethyl-2,3-dihydroxypropylglutamide,N-2,3-dihydroxypropylaspartamide or N-2,3-dihydroxypropylglutamide,N-1-hydroxymethyl-2,3-dihydroxypropylaspartam ide orN-1-hydroxymethyl-2,3-dihydroxypropylglutamide, N-bis (2-hydroxyethyl)aspartamide or N-bis(2-hydroxyethyl)glutamide, N-(3-bis(N-hydroxyethyl))aminopropylaspartamide or N-bis(2-hydroxyethyl)aspartamide or N-bis (2-hydroxyethyl) glutamide,N-(3-bis(N-hydroxyethyl))aminopropylaspartamide orN-bis(2-hydroxyethyl)aminopropylglutamide, N-p or m- oro-phenolaspartamide or N-p or m- or o-phenoglutamide andN-dihydroxyphenylaspartamide or N-dihydroxyphenylglutamide,N-2-(2-hydroxyethoxy-ethylaspartamide) or N-2- (2-hydroxyethoxy)ethylglutamide, N-2-hydroxyethylamino)ethylaspartamide orN-2-(hydroxyethylamino)ethylglutamide, N-2-methoxyethylaspartamide orN-2-methoxyethylglutamide, N-(2-o-sulfatoethyl)aspartamide orN-(2-o-sulfatoethyl)glutamide.

The more preferred oxygenated hydrocarbonamides of the formula (I) areN-2-hydroxyethylaspartamide, N-2-hydroxypropylaspartamide,N-1-methyl-2,3-dihydroxypropylaspartamide,N-1-ethyl-2,3-dihydroxypropylaspartamide andN-1-hydroxymethyl-2,3-dihydroxypropylaspartamide.

The amino acid monomer is of the general formula (II) as shown below:##STR7## wherein R³ is a radical defined by the list of amino acids andamino acid derivatives appearing below. If formula (II) is asparticacid, the aspartic acid unit in the copolymer is in its α form or β formor a mixture form of α:β ranging from 99:1 to 1:99.

The amino acids the general formula (II) (wherein M is H or metal)include alanine, arginine, aspartic acid, asparagine, cysteine,glutamine, glutamic acid, glycine, histidine, isoleucine, leucine,lysine, methionine, serine, threonine, tryptophan, tyrosine, valine,proline, and phenylalamine. The metal M is an alkaline metal, a metalion, earth alkaline metal ion or NH₄ ⁺, Al⁺³, Fe⁺³, Fe⁺², or zn⁺¹. Thefollowing amino acid derivatives can be utilized as well;hydroxyproline, γ-carboxyglutamic acids or salts thereof,o-phosphoserine, o-phosphotyrosine, o-sulfoserine, o-sulfotyrosine,o-phophothreaonine, o-sulfothreonine, s-sulfocysteine,s-phosphocysteine, side chain N-substituted asparagine with C₁ to C₃₀alkyl, aryl, alkyl or sulfoalkyl, o-sulfoaryl, o-sulfoalkyl,o-phosphoalkyl, o-phosphoaryl, o-phosphoalkyl, c-sulfonoaryl, c-sulfonoalkyl, c-sulfonoalkyl, --(--CH₂ CH₂ O--)_(s) R¹, and --(--CH₂ CH₂ NR²--)_(t) --R³, wherein R¹ and R² are H or a C₁ to C₄ alkyl group and R³is a C₁ to C₄ alkyl group, both s and t range from 1 to 50.

The repeating molar units of formulas I-α and I-β linked in thecopolymer backbone are described as the following: ##STR8##

The repeating molar units of formula II linked in the copolymer backboneare described as the following: ##STR9##

If the amino acid of formnula II is aspartic acid or its salts, theaspartic acid repeating molar units linked in the copolymer backbone aredescribed as shown below: ##STR10##

The preferred amino acids of the formula II are aspartic acid or itssalts, and glutamic acid or its salts. The more preferred amino acids ofthe formula II is aspartic acid or its salts. The aspartic acid molarunits in the copolymer chains are in the form of α-form or β-form or amixture at a ratio of α:β ranging from 1:99 to 99:1.

All D, L and DL optical sources of formula I and II monomers can beutilized. Mole ratios of the two monomer units in the polymer can rangefrom 1:99 to 99:1. Examples of effective mole ratios are provided in theexamples presented below. Preferably, the ratio of formula (I) toformula (II) ranges from 80:20 to 10:90, more preferably from 40:60 to15:85.

Appropriate dosages will depend upon the water treated and the mineralspresent in the water as indicated in the examples presented below.Effective dosages can range from 0.1 ppm to 500 ppm, more preferably 5to 50 ppm, still more preferably from 5 to 30 ppm.

By way of example, and not limitation, examples of the present inventionwill now be given. Other scales which can be reduced by using thepolymers invented are barium sulfate, calcium carbonate, calciumoxylate, calcium sulfate, etc.

EXAMPLES

The inhibitory power of the polymers of the present invention wereevaluated using activity tests employing test chemicals of reagentgrade. Specifically, calcium, magnesium, zinc and bicarbonate wererespectively supplied by reagent grade CaCl₂ ·2H₂ O, MgSO₄ ·7H₂ O, ZnSO₄·7H₂ O, and NaHCO₃ ·7H₂ O respectively. The orthophosphate was suppliedby H₃ PO₄. The polymer concentrations used in each test were indicatedin Tables 1-5.

Each test solution was stirred with a teflon coated stir bar in ajacketed glass beaker. The temperature was maintained using a Landarecirculating, constant-temperature basin. The pH was determined withFisher Accumat meter (model 6100A) and a combination electrode. The pHmeter was calibrated with two standard buffers (pH 7 and 10) andcorrections were made for temperature changes.

EXAMPLE I CALCIUM AND MAGNESIUM PHOSPHATE SCALE INHIBITION TEST

Soluble calcium and magnesium were added to provide initialconcentrations of 250 and 125 ppm as CaCO₃, respectively. An equalamount of orthophosphate (10 ppm as PO₄) was added to each testsolution, and the inhibitor concentrations are listed in Table 1. Thetemperature of the test solution was maintained at 158° F. (70° C.).Using dilute aqueous NaOH, the pH was slowly increased to 8.5 andmaintained during the four hour duration of the test. Mineral solubilitycalculations indicate that supersaturation values for the calciumphosphate of greater than 10,000 ppm and magnesium phosphate of greaterthan 600oppm were initially present. As a result, the system was underhighly a stressed condition. At the conclusion of each test, eachsolution was filtered with a 0.45 μm filter and the orthophosphateconcentration was determined spectrophotometrically after formation of ablue phosphomolybdate complex.

The inhibition of calcium and magnesium phosphate scale formation isdetermined using Equation 1 below: ##EQU1## where,filtered=concentration of phosphate ion in filtrate in the presence ofthe inhibitor of the present invention after four hours;

initial=concentration of phosphate ion in the test solution at timezero; and

blank=concentration of phosphate ion in the filtrate in the absence ofany inhibitor after four hours.

Using the above method, a number of polymer compositions were tested.The results are listed in Table 1.

                                      TABLE 1                                     __________________________________________________________________________    Calcium and Magnesium Phosphate Scale Inhibition with N-oxygenatedhydrocar    bonamide/amino acid copolymers                                                (250 ppm Ca.sup.++ /125 ppm Mg.sup.++ /10 ppm PO.sub.4 unless where it is     indicated)                                                                                                        % Phosphate salt inhibition ppm                                               polymer dose                              Sample                                                                            Polymer composition, Mol %  MW  2 3 4 5 6 7 8  10 15 20 30                __________________________________________________________________________    A1  50/50 L-2-hydroxyethylaspartamide/aspartic acid                                                           16000                                                                             9  8                                                                              23                                                                              50                                                                              67                                                                              82                                                                              86 96    98                   A1  50/50 L-2-hydroxyethylaspartamide/aspartic acid                                                           16000      4        5*                                                                              11*                                                                              35*                                                                              57*               A2  28/72 L-2-hydroxyethylaspartamide/aspartic acid                                                           33000  8   9       89    98                   A3  50/50 L-2-hydroxyethylaspartamide/aspartic acid                                                           16500                                                                             9 10                                                                              31                                                                              61                                                                              81                                                                              88                                                                              82                            A4  10/90 L-2-hydroxyethylaspartamide/aspartic acid                                                           16400  9  10       10    10                   A5  20/80 L-2-hydroxyethylaspartamide/aspartic acid                                                           16500  8  10       12    10                   A6  80/20 L-2-hydroxyethylaspartamide/aspartic acid                                                           13300  9   9       11    42                   B1  29/71 L-2-(2-methyl-1,3-dihydroxypropylaspartamide/aspartic                                               34000  9   9       86    95                   C1  polyaspartic acid           17000               8                         C2  polyaspartic acid           25000               9                         C3  polyaspartic acid           90000               4                         C4  polyaspartic acid           92000               4                         C5  polyaspartic acid           94000               6                         D1  non-biodegradable commercial product I                                                                    --     8  13       91    99                   __________________________________________________________________________     *These tests were done under high hardness stress conditions (1200 ppm        Ca.sup.++  and 10 ppm orthophosphate).                                   

EXAMPLE II IRON (HYDR)OXIDE SCALE INHIBITION TEST

In a standard test, soluble calcium and magnesium were added to provideinitial concentrations of 360 and 200 ppm as CaCO₃ respectively. Anequal amount of soluble iron (10 ppm) was added to each test solution,and the inhibitor concentrations are listed in Table 2. The temperatureof the test solution was maintained at 140° F. (60° C.). Using a diluteaqueous NaOH solution, the pH was slowly increased to 8.5 and maintainedduring the two hour duration of heating at 140° F. (60° C.). At the endof 2 hour heating period, the samples were removed from the water bathand allowed to stand undisturbed at room temperature for 24 hours. Thesamples were then taken from the top portion of each aliquot andanalyzed for iron content by atomic absorption analysis. The ironconcentration in the aliquot correlates directly with the inhibitionactivity of the polymer. That is, the higher the iron concentration inthe top part of the aliquot, the higher was the inhibition activity ofthe polymer tested.

The inhibition of iron (hydr)oxide is determined as indicated asEquation 2: ##EQU2## where, final=concentration of iron ion inunfiltered samples of the top portion after 2 hours heating and 24 hoursstanding in the presence of inhibitor;

initial=concentration of iron ion in the test solution at time zero; and

blank=concentration of iron ion in unfiltered samples of the top portionafter 2 hours heating and 24 hours standing in the absence of inhibitor.

Using the above method, a number of polymer compositions were tested.The results are listed in Table 2.

                  TABLE 2                                                         ______________________________________                                        Iron (Hydr)oxide Scale Inhibition with N-oxygenatedhydrocarbonamide/          amino acid copolymers                                                                              Iron (hydr)oxide                                                              Scale inhibition                                                              at ppm polymer dose                                      Sample                                                                              Polymer composition, Mol %                                                                     MW      3   5   10   20                                ______________________________________                                        A1    50/50 L-2-hydroxyethyl-                                                                        16000   21       92   92                                     aspartamide/aspartic acid                                               A2    28/72 L-2-hydroxyethyl-                                                                        33000    0  92  100   95                                     aspartamide/aspartic acid                                               A4    10/90 L-2-hydroxyethyl-                                                                        16400    0   0   0    5                                      aspartamide/aspartic acid                                               A5    20/80 L-2-hydroxyethyl-                                                                        16500    0   0   29   76                                     aspartamide/aspartic acid                                               A6    80/20 L-2-hydroxyethyl-                                                                        13300    4  28  --   100                                     aspartamide/aspartic acid                                               B1    29/71 L-2-(2-methyl-1,3-                                                                       34000                 85                                     dihydroxypropyl)aspartamide/                                                  aspartic acid                                                           C1    polyaspartic acid                                                                              17000            7                                     C2    polyaspartic acid                                                                              25000            14                                    C3    polyaspartic acid                                                                              90000            7                                     C4    polyaspartic acid                                                                              92000            1                                     C5    polyaspartic acid                                                                              94000            2                                     D1    non-biodegradable         0   2  100  100                                     commercial product I                                                    ______________________________________                                    

EXAMPLE III ZINC HYDROXIDE SCALE INHIBITION TEST

In a standard test, soluble calcium and magnesium were added to provideinitial concentrations of 150 and 100 ppm as CaCO₃ respectively. Anequal amount of soluble zinc (5 ppm) was added to each test solution,and the inhibitor concentrations are listed in Table 3. The testingbottles were sealed. The temperature of the test solution was maintainedat 110° F. (43° C.). Using a dilute aqueous NaOH solution, the pH wasslowly increased to 9.1 and maintained during the 24 hour duration ofthe test. At the end of 24 hour heating period, the solution wasfiltered (0.2μm) and the filtered sample was analyzed for zincconcentration by atomic absorption analysis.

The inhibition of zinc (hydr)oxide is determined as indicated asEquation 3: ##EQU3## where, filtered=concentration of zinc ion infiltrate in the presence of the inhibitor of the present invention after24 hours;

initial=concentration of zinc ion in the test solution at time zero;

blank=concentration of zinc ion in filtrate samples in the absence ofthe inhibitor of the present invention after 24 hours.

Using the above method, a number of polymer compositions were tested.The results are listed in Table 3.

                  TABLE 3                                                         ______________________________________                                        Zinc Hydroxide Scale Inhibition with                                          N-oxygenatedhydrocarbonamide/aspartic acid copolymers                                            Zinc Hydroxide Inhibition                                                     at ppm polymer dose                                        Sample                                                                              copolymer composition                                                                        MW      10      20                                       ______________________________________                                        A1    50/50 L-2-hydroxyethyl-                                                                      16000   24      71                                             aspartamide/aspartic acid                                               A4    10/90 L-2-hydroxyethyl-                                                                      16400    4      13                                             aspartamide/aspartic acid                                               A5    20/80 L-2-hydroxyethyl-                                                                      16400   75      80                                             aspartamide/aspartic acid                                               B1    29/71 L-2-(2-methyl-1,3-                                                                     34000   70      63                                             dihydroxypropyl)-                                                             aspartamide/aspartic acid                                               D1    non-biodegradable      87      92                                             commercial product I                                                    ______________________________________                                    

EXAMPLE IV CLAY PARTICULATE INHIBITION TEST

This test examines the dispersion ability of the polymers of the presentinvention for particulate matter. The assumption is that polymers whichpromote dispersancy will reduce the settling rate of clay particles andparticulate matter in general. The dispersed clay causes higherturbidity.

A standard suspension of particulate (clay) was prepared in an aqueoussolution of 300 ppm soluble calcium as CaCO₃. One liter of this solutionwas placed in a Waring blender to which 100 ml of china clay was added.The clay was dispersed for 60 seconds on low setting then immediatelydispersed equally amount in four 250ml graduated cylinders. One cylinderbecame the blank while the remaining three test inhibitor treatment. Theblank was returned to the blender and re-dispersed for 20 seconds onlow. This suspension was returned to its graduated cylinder. A samplewas withdrawn from a level of 100 ml and the turbidity was determinedwith a turbidimeter (Hach 2100A). This represented the initial readingfor blank. The suspension was returned to the graduated cylinder andallowed to settle for 2 hours. Treatment cylinders are prepared byreturning the remaining suspensions, in turn, to the blender, followedby the addition of 5 ppm inhibitor and redispersed for 20 seconds onlow. Treatment cylinders are allowed to settle for 2 hours. At the endof 2 hours, samples are withdrawn from a level of 100 ml and turbidityreadings taken.

Percent clay dispersancy is determined using the following Equation 4and the results are listed in Table 4. ##EQU4##

                  TABLE 4                                                         ______________________________________                                        Clay Particulate Dispersancy with                                             N-oxygenatedhydrocarbonamide/amino acid copolymers                                                         Clay particulate dispersancy                     Sample                                                                              copolymer composition                                                                        MW      at ppm polymer dose 5 ppm                        ______________________________________                                        A4    10/90 L-2-hydroxyethyl-                                                                      16400   40                                                     aspartamide/aspartic acid                                               A5    20/80 L-2-hydroxyethyl-                                                                      16500   32                                                     aspartamide/aspartic acid                                               A6    80/20 L-2-hydroxyethyl-                                                                      13300   52                                                     aspartamide/aspartic acid                                               B1    29/71 L-2-(2-methyl-1,3-                                                                     34000   40                                                     dihydroxypropyl)-                                                             aspartamide/aspartic acid                                               D1    non-biodegradable      50                                                     commercial product I                                                    ______________________________________                                    

EXAMPLE V POLYMER CALCIUM TOLERANCE TEST (POLYMER SOLUBILITY TEST)

This test evaluates anionic polymers for use as dispersants or scaleinhibitors. Dispersant polymers prevent deposition of suspendedparticles such as calcium and magnesium phosphate, iron (hydr)oxide,zinc hydroxide, calcium carbonate, calcium sulfate, barium sulfate,calcium oxylate clays, etc., which are either present in the make-upwater, added as treatments, or which form due to corrosion orprecipitation in the system. Hardness can be varied to determineconditions where the polymer can be an effective dispersant. This testpredicts the dispersant (scale inhibitor) activity of anionic polymers.Anionic polymers become insoluble at high calcium concentration andelevated temperature. The higher the calcium, the lower the temperatureat which turbidity occurs. Polymers tend to be good dispersants if theyare soluble at conditions of calcium and temperature. Conversely,polymers will be poor dispersants under conditions where theyprecipitate.

Dilute calcium and polymer solutions were mixed at room temperature togive 100 ppm actives and either 200 or 400 ppm soluble calcium as CaCO₃.The pH was adjusted to 8.5 with dilute NaOH solution. A thermometer wasinserted and the test vessel was covered with an aluminum foil. The testsolution was then heated gradually. The temperature was noted whenturbidity occurred.

Using this method, a number of polymers were tested and the results arelisted in Table 5. For polymers provided in accordance with the presentinvention, no turbidity was visible even after the samples reached 100°C. Additional aliquots of calcium stock solutions were added to theboiling solutions to give 800 and 1600 ppm Ca. After several minutes,there was still no turbidity. These results predict excellent dispersantand scale inhibition activity for these polymers in the presentinvention under conditions of high hardness and high temperature.

                                      TABLE 5                                     __________________________________________________________________________    Polymer Calcium Tolerance (Polymer Solubility) Test Results                                      Turbidity Temperature at ppm Calcium                       Sample                                                                            Polymer composition                                                                      MW  200 400                                                                              800 1000                                                                             1600                                         __________________________________________________________________________    A1  50/50 L-2-hydroxyethyl-                                                                  16000                                                                             CAB*                                                                              CAB                                                                              CAB -- CAB                                              aspartamide/aspartic acid                                                     copolymer                                                                 A2  28/72 L-2-hydroxyethyl-                                                                  33000                                                                             CAB CAB                                                                              CAB -- CAB                                              aspartamide/aspartic acid                                                     copolymer                                                                 C1  polyaspartic acid                                                                        17000                                                                             60° C.                                                                     -- --  -- --                                           C2  polyaspartic acid                                                                        25000                                                                             47° C.                                                                     -- --  -- --                                           D1  non-biodegradable                                                                        --  --  CAB                                                                              74° C.                                                                     -- 59° C.                                    commercial polymer I                                                      E1  non-biodegradable                                                                        --  --  -- --  CAB                                                                              --                                               commercial polymer II                                                     F1  non-biodegradable                                                                        --  55° C.                                                                     -- --  -- --                                               commercial polymer III                                                    G|  non-biodegradable                                                                        --  --  -- --  -- CAB                                              commercial polymer IV                                                     __________________________________________________________________________     *CAB = Clear At Boiling.                                                 

The data presented in Tables 1-5 demonstrate that the polymers providedin accordance with the present invention are capable of functioningpositively as a scale inhibitor and dispersant at a sufficient dose inenvironments such as cooling towers, boilers and the like. The polymersprovided in accordance with the present invention can be used alone orcombined with any other biodegradable or non-biodegradable ingredientsfor the purpose of scale inhibition and/or dispersion.

SYNTHESIS OF N-OXYGENATEDHYDROCARBONAMIDE -AMINO ACID COPOLYMERS

The above-described copolymers were synthesized using the followingprocedures. First, polysuccinimide with MW weight of 500 to 20,000 of L-or D- or DL-aspartic acid or glutamic acid was reacted with anoxygenatedhydrocarbonamine or with a mixture of anoxygenatedhydrocarbonamine and one or more otheroxygenatedhydrocarbonamine at ratios ofoxygenatedhydrocarbonamine/polysuccinimide ranging from 0.01/1.00 to0.99/1.00 in an organic solvent such as DMF, DMSO and the like or in anaqueous medium or an aqueous-organic medium at a suitable temperaturefor a suitable reaction period.

Next, the poly(succinimide of L- or D- or DL-aspartic acid) wassynthesized by heating L- or D- or DL- aspartic acid either in thepresence of an acid catalyst such as orthophosphoric acid,polyphosphoric acid, super polyphosphoric acid, a phosphonic acid (suchas HEDP, PBTC), or P₂ O₅, or a mixture of them or a sulfur-containingdehydrating agent such as sulfurtrioxide, sulfurtrioxide precursors,sulfur oxygen acids, sulfonic acids or any other acid or in the absenceof a catalyst as would be apparent to those skilled in the art and asdescribed in the journal literature. The polysuccinimide can also besynthesized from maleic anhydride and ammonium, maleic acid and ammoniumor from mono or diammonium moleate. The poly(succinimide) obtained mayor may not be purified before it is used to react with alkanolamines orother amine derivatives.

The reaction solvent is water, where the polysuccinimide is suspectedand the oxygenatedhydrocarbonamine is then added at a pH ranging from 2to 13, with a preferred pH ranging from 5 to 11. The reactiontemperature is 0° to 100° C., preferred 20° to 60° C. The reaction timeis 1 to 24 hours, preferably 2 to 10 hours. The unreactedpolysuccinimide mol units in the polymer are then hydrolyzed with a basesuch NaOH, KOH or NH₄ OH or another base to produce the copolymers orterpolymers or polypolymers. This method usually produces a polymer withhigh molecular weight.

The reaction solvent is DMF, DMSO or other organic solvents, where thepolysuccinimide is dissolved in the solvent. Theoxygenatedhydrocarbonamine or a solution of theoxygenatedhydrocarbonamine is added to the solution of thepolysuccinimide. The reaction product is then precipitated with a lesspolar solvent such as alcohol or acetone.

The precipitate is collected dried or undried and suspended in water. Abase such as NaOH is added to hydrolyze the remaining polysuccinimidemol units to produce the copolymer. The reaction conversion is usuallyquantitative. Thus, the composition (the molar ratio ofoxygenatedhydrocarbonamine/amino acid) can be controlled by controllingthe reactant molar ratio oxygenatedhydrocarbonamine/polysuccinimide. Themolecular weight of the resulting copolymer can be controlled bycontrolling the reaction temperature and reaction time as well as themolecular weight of the starting polysuccinimide.

Specific examples of copolymers are listed in Table 6 and the synthesisof those examples is explained below.

For polymer numbers 4 and 5 of Table 6 a solution of ethanolamine (1.53g, 0.025 mol 1.0 equivalent) in deionized water was added to amagnetically stirred suspension of polysuccinimide (2.5 g, 0.025 mol) indeionized water (20.4 g) over a 17 minute period. The suspension wasstirred at room temperature for 28 hours. Almost all solids disappearedwithin 50 minutes to form a clear solution. The pH range was thenadjusted from 9.4 to 8.7 to afford crudeN-2-hydroxyethylaspartamide/aspartic acid copolymer. Dialysis of polymerno. 4 to afford pure (polymer no. 5). The product molecular weightsdetermined by GPC and compositions determined by ¹³ C NMR spectroscopyare summarized in Table 6.

Polymer No. 1 was similarly prepared but only 0.50 equivalent ofethanolamine was charged. After a suspension of polysuccinimide (5.0 g,0.050 mol) in deionized water (35 g) was stirred with ethanolamine (1.53g, 0.0251 mol, 0.50 equivalents) at room temperature for 20.8 hours,0.041 moles of NaOH solution was added dropwise to form a clear solutionof pH 12.98. The solution was further stirred for 1 hour and thenneutralized with dilute HCl to pH 6.7. Dialysis (membrane MWCO 12 to14K) of the crude product afforded polymer No. 1. ¹³ C NMR analysisindicated that most of residual ethanolamine was not removed. Themolecular weight and ethanolamine incorporation are summarized in Table6.

Polymer No. 2 was prepared by adding dry DMF (60 g) and ethanolamine(4.66 g, 0.0765 mol, 0.50 equivalent) in dry DMF(10 ml) to a stirredpowder of polysuccinimide (15.0 g, 0.153 mol) in a 250 ml flask. Thesolution was stirred at room temperature for 4 hours and at 120° to 150°C. for 1 hour 35 min. After the solution was cooled to room temperature,200 ml of ethanol was added. The precipitate was filtered in vacuum,dried at 70° to 80° C. and vacuumed to give 9.7 g of solids. The solidswere ground and suspended in deionized water (60 g). A NaOH solution(4.1 g of 50% NaOH and 7.0 g of deionized water) was added over 25minutes at pH less than or equal to 11.8. The resultant solution wasfurther stirred for 50 minutes and then neutralized to pH 7.5 to affordalmost pure ethanolamine-polyaspartic acid. Part ofN-2-hydroxyethylaspartamide/aspartic acid copolymer was dialyzed(membrane MWCO 500) for 30 hours. The dialyzed solution was concentratedto give pure polymer No. 2. The product molecular weight determined byGPC and composition determined by ¹³ C NMR spectroscopy are summarizedin Table 6.

Polymer No. 19 was prepared as follows: 2-amino-2-methyl-1,3 propanediol(1.39 g, 0.0125 mol) in dry DMF (10 ml) was added to a stirred solutionof polysuccinimide (1.23 g, 0.0125 mol) in dry DMF (15 g). After thesolution was stirred at room temperature for 20 hours, 150 ml of 1:2ethanol/cyclohexane was added. The resultant precipitate wascentrifuged. The supernatant was decanted and the solids was washed withethanol. This procedure was repeated once. The solids were dried at 50°C. under a vacuum and then suspended in deionized water. 5.0g of 10.0%NaOH solution was added dropwise to the stirred suspension to form aclear solution. The solution was acidified to pH 2.1 and then dialyzed(membrane MWCO 12 to 14K) for 3 days. The dialyzed solution wasconcentrated to afford pure polymer no. 16. The product MW determinedwith GPC and composition determined with ¹³ C NMR spectroscopy aresummarized in Table 6.

For polymer No. 22, to a stirred solution of poly(suc) (10.0g, 0.102mol) in DMF (80 ml) was added dropwise a solution of ethanolamine (1.87g, 0.0306 mol) in DMF (15 ml). The solution was further stirred at roomtemperature for 15 hours. SO₃ ·DMF(14.0 g, 0.092 mol) and pyridine(10.0g) were added. The solution was stirred at 22°-40° C. for 24 hours.180 ml of ethanol was added. The precipitated polymer product wascollected by filtration, dried in vacuo, ground and suspended indeionized water (60 g). 50% of NaOH (8.16 g) was added dropwise to thestirred suspension at pH≦11 to afford crude EAS/ASP copolymer. Dialysisof the crude product gave pure EAS/ASP copolymer polymer No. 22. Theproduce MW determined with GPC and composition determined with ¹³ C NMRspectroscopy are summarized in Table 6.

Examples of the copolymers synthesized in addition to those discussedabove are listed in Table 6.

                                      TABLE 6                                     __________________________________________________________________________    Examples of N-oxygenatedhydrocarbonamide/amino acid Copolymers                      MW of                                                                             M % of alkanol                                                                       reaction                                                                            reaction                                                                          reaction                                                                           product                                                                             product                                 polymer No.                                                                         polysuc                                                                           amine charged                                                                        temp & time                                                                         medium                                                                            conversion                                                                         composition                                                                         MW                                      __________________________________________________________________________     1.   94000                                                                             50% EA*                                                                              rt, 20 h                                                                            water                                                                             56%  28/72 33000                                                                   HEA/ASP.sup.b                                  2.   72000                                                                             50% EA rt, 4 h                                                                             DMF 100  50/50 16000                                                    120-50° C.,                                                                           HEA/ASP                                                        1.5 h                                                         3.   72000                                                                             50% EA rt, 4 h                                                                             DMF 100  50/50 16500                                                    120-50,        HEA/ASP                                                        1.4 h                                                         4.   66000                                                                             100% EA                                                                              rt, 27 h                                                                            water                                                                              30  30/70 60000                                                                   HEA/ASP                                        5.   --  --     --    --  --   28/72 33000                                                                   HEA/ASP                                        6.   48000                                                                             10% EA rt, 3.3 h                                                                           DMF 100  10/90 16400                                                    120-50,        HEA/ASP                                                        1.6 h                                                         7.   48000                                                                             20% EA rt, 4 h                                                                             DMF 100  20/80 16500                                                    120-65,        HEA/ASP                                                        1.2 h                                                         8.   72000                                                                             4% EA  rt, 4 h                                                                             DMF 100  4/96   9400                                                    12-65° C.,                                                                            HEA/ASP                                                        4.2 h                                                         9.   --  --     --    --  --   6/94   9600                                                                   HEA/ASP                                       10.   72000                                                                             6% EA  150-80° C.,                                                                  DMF 100  6/94   7100                                                    5 h            HEA/ASP                                       11.   48000                                                                             35% EA rt, 4 h                                                                             DMF 100  35/65  9400                                                    130-75° C.,                                                                           HEA/ASP                                                        1.3 h                                                        12.   48000                                                                             30% EA rt, 4 h                                                                             DMF 100  30/70 10000                                                    120-60° C.,                                                                           HEA/ASP                                                        1 h                                                          13.   48000                                                                             25% EA rt, 5h                                                                              DMF 100  25/75 11000                                                    140-55° C.,                                                                           HEA/ASP                                                        0.9 h                                                        14.   48000                                                                             40% EA rt, 3.5 h                                                                           DMF 100  40/60  8300                                                    120-60° C.,                                                                           HEA/ASP                                                        1.3 h                                                        15.   48000                                                                             27% EA rt, 4.4 h                                                                           DMF 100  30/70 29000                                                    80-100° C.,                                                                           HEA/ASP                                                        1 h                                                          16.   48000                                                                             30% EA rt, 5 h                                                                             DMF 100  30/70 35000                                                    110-30° C.,                                                                           HEA/ASP                                                        0.5 h                                                        17.   48000                                                                             80% EA rt, 3 h                                                                             DMF 100  80/20 13300                                                    120-65° C.,                                                                           HEA/ASP                                                        1.3 h                                                        18.   48000                                                                             30% APO.sup.c                                                                        rt, 22 h                                                                            DMF 100  30/70 37000                                                    60-80° C.,                                                                            HPA/ASP.sup.d                                                  1 h                                                          19.   94000                                                                             100% AMPD.sup.e                                                                      rt, 20 h                                                                            water                                                                              29  29/71 34000                                                                   MDHA/ASP.sup.f                                20.   94000                                                                             10% Tris.sup.g                                                                       50° C., 5 h                                                                  DMF  10  10/90 46000                                                                   Tris/ASP.sup.h                                21.   72000                                                                             7% MEA.sup.i                                                                         rt, 2 h                                                                             DMF 100  7/93  10700                                                    rt-145° C.,                                                                           MEA/ASP.sup.j                                                  1.3 h                                                                         145-                                                                          160° C.,                                                               0.5 h                                                        22.   72000                                                                             30% EA rt, 15 h                                                                            DMF  98  29/71 51000                                                    then           SEA/ASP.sup.k                                                  SO.sub.3 @DMF/                                                                py 22-40,                                                                     24 h                                                         __________________________________________________________________________     .sup.a EA: ethanolamine.                                                      .sup.b HEA/ASP copolymer = N(2-hydroxyethyl)aspartamide/aspartic acid         copolymer:                                                                    .sup.c APO: 1amino-2-propanol.                                                .sup.d HPA/ASP copolymer: N(2-hydroxypropyl)aspartamide/aspartic acid         copolymer.                                                                    .sup.e AMPD: 2amino-2-methyl-1,3-propanediol.                                 .sup.f N(1-methyl-2,3-dihydroxypropyl)aspartamide/aspartic acid copolymer     .sup.g Tris: tris(hydroxymethyl) amino methane.                               .sup.h Tris: N(1-hydroxymethyl-2,3-dihydroxypropyl)aspartamide/aspartic       acid copolymer.                                                          

This invention is applicable to industries where scale inhibition inaqueous systems is desirable, such as industries using cooling towersand the like. Copolymers comprising at least one ofN-oxygenatedhydrocarbonamides and at least one of amino acids in amountsranging from 0.1 to 500 ppm may be used alone or in combination with oneor more scale inhibitors such as polyacrylate, polymethylacrylate, acopolymer of acrylic acid and methacrylic acid, a copolymer of acrylicacid and acrylamide, polymaleic anhydride, a copolymer of acrylic acidand maleic acid copolymer, polyol esters,1-hydroxyethylidene-1,1-diphosphonic acid,2-phosphono-butane-1,2,4-tricarboxylic acid (PBTC), amino tri(methylenephosphonic acid), an acrylic acid/acrylamide/amino methane sulfonateterpolymer, polyaspartic acid and mixtures thereof. Such combinedcompositions may exert a synergistic effect in terms of corrosioninhibition, scale inhibition and dispersancy.

Copolymers comprising at least one of N-oxygenatedhydrocarbonamides andat least one of amino acids in amounts ranging from 0.1 to 500 ppm mayalso be used alone or in combination with one or more yellow metalcorrosion inhibitors such as benzotriazole, tolyltriazole,mercaptobenzothiazole and other azole compounds. Such combinations mayexert a synergistic effect in terms of corrosion inhibition.

Copolymers comprising at least one of N-oxygenatedhydrocarbonamide andat least one of amino acids in amounts ranging from 0.1 to 500 ppm mayalso be used alone or in combination with one or more other corrosioninhibitors such as phosphorous containing inorganic chemicals such asphosphates, pyrophosphates, polyphosphates; hydroxycarboxylic acids ortheir salts such as gluconic acid, glucaric acid; Zn²⁺, Ce²⁺, MoO₄ ²⁻,VO₃ ²⁻, WO₄ ²⁻. Such combinations may exert a synergistic effect interms of corrosion inhibition.

Copolymers comprising at least one of N-oxygenatedhydrocarbonamides andat least one of amino acids in amounts ranging from 0.1 to 1000 ppm mayalso be used alone or in combination with one or more biocides such asoxidizing biocides, e.g., Cl₂, NaOCl, NaOBr, or nonoxidizing biocides,e.g., glutaldehyde, isothiazolinones (i.e.,5-chloro-2-methyl-4-isothiazolin-3-one or 2-methyl-4-isothiazoli-3-one)or Kathon WT (a product of Rohm and Hass Company of Philadelphia Pa.),sulfamic acid-stabilized bleach and sulfamic acid-stabilized bromine.Such combinations may exert a synergistic effect in terms of corrosioninhibition, scale inhibition and bacterium control.

In addition, copolymers comprising at least one ofN-oxygenatedhydrocarbonamides and at least one of amino acids in amountsranging from 0.1 to 1000 ppm may be used alone or in combination withscale inhibitors, yellow metal corrosion inhibitors, biocides and otherchemical additives.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its attendant advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

What is claimed:
 1. A compound for reducing mineral scale accumulationon metallic surfaces that come in contact with an industrial water, thecompound comprising:a polymer comprising units of at least one ofN-oxygenatedhydrocarbonamide monomers and units of at least one of aminoacid monomers or derivatives thereof.
 2. The compound of claim 1,wherein the N-oxygenatedhydrocarbonamide further comprises aN-oxygenatedhydrocarbonamide salt.
 3. A compound for reducing mineralscale accumulation on metallic surfaces that come in contact with anindustrial water, the compound comprising:a polymer comprising units ofat least one of n-oxygenatedhydrocarbonamide monomers and units of atleast one of amino acid monomers, wherein theN-oxygenatedhydrocarbonamide has the formula ##STR11## wherein M isselected from the group consisting of hydrogen, alkaline earth metals,alkali metals, NH₄ ⁺, Al⁺³, Fe⁺², Fe⁺³ and Zn⁺¹ ; n is selected from thegroup consisting of 1 and 2; m ranges from 1 to 10; Y is selected fromthe group consisting of H, an alkyl group and SO₃ M¹ and mixturesthereof, wherein M¹ is selected from the group consisting of H, alkalineearth metals and alkali metals; R¹ is selected from the group consistingof hydrogen, an alkyl group and an aryl group; X is selected from thegroup consisting of alkylene and arylene.
 4. A compound for reducingmineral scale accumulation on metallic surfaces that come in contactwith an industrial water, the compound comprising:a polymer comprisingunits of at least one of n-oxygenatedhydrocarbonamide monomers and unitsof at least one of amino acid monomers, wherein theN-oxygenatedhydrocarbonamide has the formula ##STR12## wherein M isselected from the group consisting hydrogen, alkaline earth metals,alkali metals, NH₄ ⁺, Al⁺³, Fe⁺², Fe⁺³ and Zn⁺¹ ; n is selected from thegroup consisting of 1 and 2; m ranges from 1 to 10; Y is selected fromthe group consisting of H, an alkyl group and SO₃ M¹ and mixturesthereof, wherein M¹ is selected from the group consisting of H, alkalineearth metals and alkali metals; R¹ is selected from the group consistingof hydrogen, an alkyl group and an aryl group; X is selected from thegroup consisting of alkylene and arylene.
 5. A compound for reducingmineral scale accumulation on metallic surfaces that come in contactwith an industrial water, the compound comprising:a polymer comprisingunits of at least one of n-oxygenatedhydrocarbonamide monomers and unitsof at least one of amino acid monomers, wherein theN-oxygenatedhydrocarbonamide has a formula selected from the groupconsisting of ##STR13## wherein M is selected from the group consistinghydrogen, alkaline earth metals, alkali metals, NH₄ ⁺, Al⁺³, Fe⁺², Fe⁺³and Zn⁺¹ ; n is selected from the group consisting of 1 and 2; m rangesfrom 1 to 10; Y is selected from the group consisting of H, an alkylgroup and SO₃ M¹ and mixtures thereof, wherein M¹ is selected from thegroup consisting of H, alkaline earth metals and alkali metals; R¹ isselected from the group consisting of hydrogen, an alkyl group and anaryl group; X is selected from the group consisting of alkylene andarylene.
 6. The compound of claim 5, wherein R¹ has from one to thirtycarbon atoms.
 7. The compound of claim 5, wherein R¹ is substituted withat least one group selected from the group consisting of OH, SO₃ M(wherein M is selected from the group consisting of H, an alkaline earthmetal, and an alkali metal, PO₃ M₂ (wherein M₂ is selected from thegroup consisting of H an alkaline earth metal and an alkali metal) andCOM (wherein M is selected from the group consisting of OH, OR, and NR₂wherein R₂ is an alkyl group).
 8. The compound of claim 5, wherein X hasfrom one to thirty carbon atoms.
 9. The compound of claim 5, wherein Xis straight chained alkylene or X is an arylene.
 10. The compound ofclaim 5, wherein X is branched chained alkylene or X is an arylene. 11.The compound of claim 3, wherein X comprises a straight orbranched-chain alkylene group or an arylene group substituted with oneor more OH, SO₃ M³ (wherein M³ is selected from the group consisting ofH alkaline earth metals and alkali metals) PO₃ M⁴ ₂ (wherein M⁴ isselected from the group consisting of H, alkaline earth metals andalkali metals, COM⁵ (wherein M⁵ is selected from the group consisting ofOH, OR, and NR₂ wherein R₂ is an alkyl group).
 12. The compound of claim1, wherein the amino acid is selected from the group consisting ofalanine, arginine, aspartic acid, asparagine, cysteine, glutamine,glutamic acid, glycine, histidine, isoleucine, leucine, lysine,methionine, serine, threonine, tryptophan, tyrosine, valine, proline andphenylalanine, hydroxyproline, γ-carboxyglutamic acids, salts ofγ-carboxyglutamic acids, o-phosphoserine, o-phosphotyrosine,o-sulfoserine, o-sulfotyrosine, o-phosphothreonine, o-sulfothreonine,s-sulfocysteine, s-phosphocysteine, side chain N-substituted asparaginewith C₁ to C₃₀ alkyl, aryl, sulfoalkyl, o-sulfoaryl, o-phosphoaryl,o-phosphoalkyl, c-sulfonoalkyl, --(--CH₂ CH₂ O--)_(s) --R¹, or --(--CH₂CH₂ NR² --)_(t) --R³, wherein R¹ and R² are selected from the groupconsisting of H and a C₁ to C₄ alkyl group and R³ is a C₁ to C₄ alkylgroup, both s and t range from 1 to
 50. 13. The compound of claim 1,wherein the N-oxygenatedhydrocarbonamide is selected from groupconsisting of N-2-hydroxyethylaspartamide, N-2-hydroxyethygutamide,N-3-hydroxypropylaspartamide, N-3-hydroxypropylglutamide,N-2-hydroxypropylaspartamide, N-2-hydroxypropylglutamide, N-1-methyl-2,3-dihydroxypropylaspartamide, N-1-methyl-2, 3-dihydroxypropylglutamide,1-ethyl-2, 3-dihydroxypropylaspartamide,1-ethyl-2,3-dihydroxypropylglutamide, 2,3-dihydroxypropylaspartamide,N-2, 3-dihydroxypropylglutamide, N-1-hydroxymethyl-2, 3-dihydroxypropylaspartamide, N- 1-hydroxymethyl -2,3-dihydroxypropylglutamide, N-bis (2-hydroxyethyl) aspartamide,N-bis(2-hydroxyethyl)glutamide,N(3-bis(N-hydroxyethyl))aminopropylaspartamide, N-(3-bis(N-hydroxyethyl)) aminopropylglutamide, N-p-phenolaspartamide orN-p-phenolglutamide, N-m-phenolaspartamide, N-m-phenolglutamide,N-o-phenolaspartamide, N-dihydroxyphenylaspartamide,N-dihydroxyphenylglutamide, N-2-(2 -hydroxyethylamino)ethylaspartamide,N-2-(2-hydroxyethylamino)ethylglutamide, N- 2-methoxyethylaspartamide,N-2-methoxyethylglutamide, N-(2-o-sulfatoethyl)aspartamide,N-(2-o-sulfatoethyl)glutamide, N-2-(2-hydroxyethoxy)ethylaspartamide,and N-2-(2-hydroxyethoxy)ethylglutamide.
 14. A solution comprising:anindustrial process water; and a polymer comprising at least oneN-oxygenatedhyrdocarbonamide monomer unit and at least one amino acidmonomer unit, or derivative thereof wherein the amino acid is selectedfrom the group consisting of alanine, arginine, aspartic acid,asparagine, cysteine, glutamine, glutamic acid, glycine, histidine,isoleucine, leucine, lysine, methionine, serine, threonine, tryptophan,tyrosine, valine, proline, phenylalanine, hydroxyproline,γ-carboxyglutamic acids, salts of γ-carboxyglutamic acids,o-phosphoserine, o-phosphotyrosine, o-sulfoserine, o-sulfotyrosine,o-phosphothreonine, o-sulfothreonine, s-sulfocysteine,s-phosphocysteine, side chain N-substituted asparagine with C₁ to C₃₀alkyl, aryl, sulfoalkyl, o-sulfoaryl, o-phosphoaryl, o-phosphoalkyl,c-sulfonoalkyl, --(--CH₂ CH₂ O--)_(s) --R¹, o--(--CH₂ CH₂ NR² --)_(t)--R³, where R¹ and R² are H or a C₁ to C₄ alkyl group and R³ is a C₁ toC₄ alkyl group, both s and t range from 1 to
 50. 15. A solutioncomprising:an industrial process water; and a polymer comprising atleast one N-oxygenatedhydrocarbonamide monomer unit and at least oneamino acid monomer unit, wherein the N-oxygenatedhydrocarbonamide isselected from group consisting of N-2-hydroxyethylaspartamide,N-2-hydroxyethylglutamide, N-3-hydroxypropylaspartamide,N-3-hydroxypropylglutamide, N-2-hydroxypropylaspartamide,N-2-hydroxypropylglutamide, N-1-methyl-2, 3-dihydroxypropylaspartamide,N-1-methyl-2,3-dihydroxypropylglutamide, 1-ethyl-2, 3-dihydroxypropylaspartamide, 1-ethyl-2,3-dihydroxypropylglutamide,2,3-dihydroxypropylaspartamide, N-2, 3-dihydroxypropylglutamide,N-1-hydroxymethyl -2,3 -dihydroxypropylaspartamide, N-1-hydroxymethyl-2,3-dihydroxypropylglutamide, N-bis (2-hydroxyethyl) aspartamide, N-bis (2-hydroxyethyl) glutamide, N (3 -bis(N-hydroxyethyl))aminopropylaspartamide, N- (3-bis (N-hydroxyethyl))aminopropylglutamide, N-p-phenolaspartamide or N-p-phenolglutamide,N-m-phenolaspartamide, N-m-phenolglutamide, N-o-phenolaspartamide,N-m-phenolglutamide, N-dihydroxyphenylaspartamide,N-dihydroxyphenylglutamide, N-2(2-hydroxyethylamino)ethylaspartamide,N-2 - (2 -hydroxyethylamino) ethylglutamide,N-2-methoxyethylaspartamide, N-2-methoxyethylglutamide, N-(2-o-sulfatoethyl)aspartamide, N- (2-o-sulfatoethyl) glutamide, N-2-(2-hydroxyethoxy) ethylaspartamide, and N-2- (2-hydroxyethoxy)ethylglutamide.
 16. The solution of claim 15 further comprising mineralsselected from the group consisting of alkaline earth metal phosphates,alkaline earth metal sulfates, alkaline earth metal carbonates, iron(hydro)oxides, zinc hydroxides, manganese oxides, aluminum(hydro)oxides, clays and silicates.
 17. The solution of claim 15 furthercomprising at least one scale inhibitor chosen from the group consistingof polyacrylate, polymethylacrylate, a copolymer of acrylic acid andmethacrylic acid, a copolymer of acrylic acid and acrylamide, polymaleicanhydride, a copolymer of acrylic acid and maleic acid polyol esters,1-hydroxyethylidene-1,1-diphosphonic acid,2-phosphono-butane-1,2,4-tricarboxylic acid (PBTC), amino tri(methylenephosphonic acid), an acrylic acid/acrylamide/amino methane sulfonateterpolymer, polyaspartic acid and mixtures thereof.
 18. The solution ofclaim 15 further comprising at least one yellow metal corrosioninhibitor selected from the group consisting of benzotriazole,tolyltriazole, mercaptobenzothiazole and other azole compounds.
 19. Thesolution of claim 15 further comprising at least one corrosioninhibitor.
 20. The solution of claim 15 further comprising at least onebiocide selected from the group consisting of Cl₂, NaOCl, NaOBr,glutaldehyde, isothiazolinones, sulfamic acid-stabilized bleach andsulfamic acid-stabilized bromine.